Personal mobile devices can perform a communication by constructing an LR-WPAN (low-rate wireless personal area networks). As an example of the LR-WPAN, there is a network following IEEE 802.15.4 standard. IEEE 802.15.4 standard provides transmission speed of 20 Kbps and 40 Kbps on 868/915 MHz band using a BPSK (binary phase-shift keying) and provides transmission speed of 250 Kbps on 2.45 GHz band using an O-QPSK (offset quadrature phase-shift keying). IEEE 802.15.4b standard also provides transmission speed of 250 Kbps on 868/915 MHz band using the O-QPSK.